Force measurement device for controlling the position of an implement for towing by an agricultural machine

Abstract

A force measuring device for an implement for towing an agricultural machine comprising at least one connection arm between the implement and a flexure bar mounted on said agricultural machine, at least one lever connecting the arm to a control system, wherein said control system comprises an electrical circuit arranged to control the movement of the lever by means of a mechanical and/or hydraulic member, the electrical circuit comprising at least one resistive element fixed to a portion of the flexure bar, the resistive element being constructed of a material the resistance of which is proportional to the deformation which the element undergoes when in use.

What we claim is: 
     
       1. A resistive force measurement device for an implement towed behind an agricultural machine, comprising a flexure bar mounted on said agricultural machine, at least one connection arm between said implement and said flexure bar, a control system, at least one lever connecting said arm to said control system, said control system comprising an electrical circuit arranged to control the movement of said lever by means of a mechanical and/or hydraulic member, wherein said electrical circuit comprises at least one resistive element integral with a portion of said flexure bar and capable of measuring a resistive force parallel to the ground, and at least one resistive element integral with a portion of said flexure bar and capable of measuring a resistive force perpendicular to the ground, so that the resistance of said implement is proportional to the deformation which said resistive elements undergo when in use, said resistive elements being fused upon an electric insulating material which is fixed to said flexure bar. 
     
     
       2. The device of claim 1, wherein said flexure bars are provided with two first seats, on each of which is mounted at least one of said resistive elements, said first seats lying respectively in two parallel horizontal planes, and two second seats, on each of which is mounted at least one of said resistive elements, said second seats lying respectively in two vertical planes, said resistive elements on said first and second seats in respective perpendicular planes being connected to adjacent sides of a Wheatstone bridge. 
     
     
       3. The device of claim 1, wherein said resistive elements are of the thick film type. 
     
     
       4. The device of claim 1 in which said resistive elements are of the metal film type. 
     
     
       5. The device of claim 1 in which said resistive elements are of the semiconductor type.